Gas-conversion apparatus



March 27? 1954" F. P. WLsoN, JR

GAS CONVERSION APPARATUS Filed March 6,

, Irv/erich: Frederick P Wlsondn;

Patented Mar. 27, 1934 PATENT OFFICE GAS-CONVERSION APPARATUS FrederickP. Wilson, Jr.

, Schenectady, N. Y., as-

sgnor to General Electric Company, a corporation of New York Application6, i930, Serial No.. s133325 3 maints.

The present invention relates to the manufacture of combustible gashaving a high hydrogen content and either a predetermined low content ofhydrocarbon gas or being substantially free from hydrocarbon gas asdesired.

It is the object of my invention to produce a gas mixture suitable forsuch industrial operations as the bracing and annealing or metals,electric welding involving dissociated or atomic hydrogen, the cuttingof metals by a flame, the reduction of metals from their oxides andother purposes requiring a gas having reducing properties.

My invention comprises an apparatus for treat- 16 ing a hydrocarbon gas,or a gaseous mixture containing a hydrocarbon gas, at an elevatedtemperature which is chosen and maintained to cause to be derived fromsuch hydrocarbon a gaseous product of predetermined composition, suchgas 20 either being substantially non-carburizing or having acontrollable carburizing or decarburizing property.

IMy new gas generator is adapted to provide in steady, regulated volumea non-carburizing reducing gas, such as hydrogen or carbon monoxide, orboth, which is either substantially' unassocat-ed with hydrocarbon gasor contains a predetermined, denite proportion oi' a stable,` normallygaseous hydrocarbon, such as methane $0 with or without inactive gasessuch as nitrogen.

A typical gaseous product made by the practice of my invention comprisesabout 75 per cent of hydrogen, about 20 per cent carbon monoxide, andabout l per cent of methane, the remainder $5 being inactiveconstituents, such as nitrogen.

The novel features of my invention are set forth with greaterparticularity in the accompanying claims. For a complete understandingof my invention reference may be had to the fol- 40 lowing descriptiontaken together with the accompanying drawing in which Fig. 1 is asomewhat conventionalized side elevation illustrating the relation ofmixing device, gas reaction chamber, and steam control device; Fig. 2 isa vertical section of a reaction chamber for subjecting gaseous mixturesto a predetermined high temperature; and Fig. 3 is a. side elevationillustrating a modified gas feed apparatus.

Referring to the drawing, a carbon-containing gas, such as a fuel gas ofthe character employed for city gas supply, which commonly comprises asubstantial proportion of normally gaseous hydrocarbons, is introducedby a supply pipe 3 to a mixing device 4. Such a fuel gas usuallycomprises hydrogen, carbon monoxide, methane and (Cl. 48m-65) higherhydrocarbons ci the methane series con monly known as illuminants. Asexamples of such gas, coal gas, natural gas, coke oven gas and producergas may be mentioned. A hydrocarbon gas such as butane may be employed.so Steam may be admitted to the mixing device by a supply pipe 5, thesteam flowing through a valve 6, which is controlled by atemperature-responsive device 7, whereby the amount of steam admixedwith the hydrocarbon gas is controlled. @g q'lhe device 'i' operates tovary the steam supply in response to the temperature of the gas-steammixture in the chamber 4 so as to maintain a constant ratio of gas andsteam in the reaction mixture delivered to the reaction chamber 8 by thepipe 9, emerging from the mixing device. Imay use for elements 6 and 7,a steam controller such as sold in the open market for controlling steamlow in response to temperature variations. Thermostatic or pyrometeroperated electric apparatus for varying the steam supply likewise may beused. Such devices are known in the art and hence will not be heredescribed. The steam controller comprises a steam valve operated by amechanism which. is responsive to the a 'temperature of a medium (inthis case the ture in e) through the intermediary o a gas, or other uid,under pressure. The temperature of the gaseous mixture in the chamber 4may be observed from a thermometer 11. Its temperature will vary withthe rate of steam flow.

With a proper setting of the control device, the ratio of gas and steamis maintained constant regardless of variations of gas or steampressure. Should the ratio of steam tend to fall, then the temperatureof the mixture in the chamber 4 will fall and the device 'l will openthe steam valve causing more steam to be admitted. Conversely a rise insteam ratio will result in an increased liberation of heat in the mixingchamber and cause the device 7 to reduce the flow of steam by reducingthe aperture of the ,steam valve. as already stated above, the steamadmixture may be omitted. In that event dissociated carbon accumulatesin the reaction chamber and should be removed from time to time.

The gas, or gas and steam, mixture passes from the pipe 9 through a heatinterchanger 10 to the reaction chamber 8 where it is subjected to atemperature within the range of about '100 to 1100 C., causingdissociation and if steam is present causing the dissociated carbon toreact with the water vapor to form hydrogen and carbon monoxide.Ordinarily a. temperature of about 1000o C. is employed. At thistemperature ist a small amount of methane (about 1%) remains in thereaction product. For many industrial operations this amount ofhydrocarbon residue either is not harmful, or is desirable and benecial,particularly for carrying out brazing operations such as described inUnited States Patent 1,528,581, issued March 3, 1925, to ChristianSteenstrup. If a greater amount of hydrocarbon gas is desired as forcarburizing metals, a lower temperature is employed in the reactionchamber. At a temperature of about 1100 C., the decomposition of thehydrocarbon gas is so nearly complete into hydrogen and carbon that theremaining hydrocarbon is negligible. Even higher temperatures may beemployed if desired to entirely eliminate the hydrocarbon. If Watervapor is present in proper proportion the carbon is completely convertedto carbon monoxide at 1000" C.

As illustrated in Fig. 2, the reaction chamber comprises a metal shell12 within which is located a rebrick Wall 13, resting on a base 14.Mounted on the wall 13 is a distributing chamber 15 which communicatesby a conduit 16 with the heat interchanger 10 and in fact constitutespart of the heat interchanger. 'The shell 12 is lined With a nelydivided heat insulator 1'7, such as inely divided silica. An electricresistor 18 is supported by hangers 19 of refractory material, which arebuilt into the wall 13 and project therefrom. This resistor preferablycomprises a pleated ribbon of nickel-chromium alloy which has anincidental catalyzing effect upon the gaseous reaction or gasifyingoccuring in the reaction chamber but principally functions to radiatesufficient heat to produce a desired high temperature in the reactionmixture. Suitable external electric regulating devices (not shown) maybe used to control the temperature of the electric heater.

The gas mixture entering the chamber 15 passes through the iron tubes20, in which it becomes heated, to a region near the bottom o theconverter and passes upward in a counter current path in contact withthe resistance heater and adjacent heated parts whereby chemicalequilibrium is established and a product of desired definite andmaintained composition is formed. The gaseous product emerges from thereaction zone by the conduit 21 and may be supplied to a brazing furnaceor other industrial device. In a brazing furnace a content of carbonmonoxide is desirable to prevent oxidation of ferrous metal duringcooling. A content of hydrocarbon gas in the neighborhood of one percent is desirable to combine with water vapor which is unavoidablypresent in a brazing furnace.

The gaseous product, which is constituted mainly of hydrogen, and carbonmonoxide, togetner, with an exactly predetermined proportion ofhydrocarbon gas, is suitable for many metallurgical operations in whichthe c arbon content of the metal should be accurately controlled. Forsuch operations a furnace or oven atmosphere can be maintained neutral,decarburizing or carburizing by the practice of my invention. In acopending application Serial No. 433,726, filed March 6, 1930, I havedescribed and claimed metallurgical apparatus and processes employingsuch gaseous products as an enveloping atmosphere.

Some nitrogen, say about 4 or 5 per cent, is usually present in the fuelgas commonly furnished by city gas companies. For .503.11 metalresaca?lurgical operations a larger proportion of diluent is desirable. Forsome purposes a nitrogen content as high as 95 per cent is employed, therest of the mixture consisting of hydrocarbon or carbon monoxide. Such amixture is non-innammable and when dry is reducing chemically.

If it is desired to produce a gaseous mixture for metallurgicaloperations having a substantial content of inactive gas, such asnitrogen, and carbon dioxide, some of the fuel gas fed to the converteris iirst burned by mixing with such amount of air that incompletecombustion is produced. In that event a modied gas feeding system isemployed as is illustrated in Fig. 3. In this gure a combustion chamber23 is inserted into the gas supply line 3 by closing the valve 24 andopening the valve 25 in a supply pipe 26 of the combustion chamber,which is also supplied with air or other combustible gas under pressurethrough a pipe 27. A flame is produced at the oriiice of the air supplypipe 27 which burns in the surrounding atmosphere of fuel gas in thecombustion chamber 23 and consumes part of the fuel gas forming carbondioxide, carbon monoxide, and water vapor. These products, together withthe nitrogen introduced as part of the air, are carried through the pipe28 into the mixing chamber 4. It is desirable in some cases to removethe Water vapor from the gaseous mixture in pipe 28. rlhis can be donein any convenient Way, as for example by passing the gases through acondenser 29 and drawing on the condensed Water. 1n some cases the watervapor may be retained in the gaseous mixture and a correspondinglylesser quantity of steam admitted to the mixing chamber, so as not todisturb the gas and steam ratio. The hydrocarbon gas in some cases maybe wholly decomposed and oxidized in the combustion chamber 23, thereaction chamber 4 then being unnecessary.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A gas generator comprising the combination of means for mixing unlikegases in predetermined proportions, a distributing chamber communicatingwith said mixing means, a reaction chamber, conduit means communicatingat one end with said distributing chamber, being open at the oppositeend to said reaction chamber, and projecting into said reaction chamber,a radiant heater located in said reaction chamber, said heater beingconstructed to produce the high temperature at which a gaseous mixturepassing through and emanating from said conduit means will chemicallyreact, and an outlet conduit for said reaction chamber.

2. A gas generator comprising the combination of a device for mixingunlike gases capable of chemical reaction, means for maintaining saidgases in predetermined ratio at different feed pressures, a distributingchamber communicating with said device, a reaction chamber, a commonheat-insulating enclosure enveloping said distributing and reactionchambers, a plurality of tubes each communicating at one end with saiddistributing chamber, extending through a substantial part of saidreaction chamber and at the opposite end having orifices communicatingwith said reaction chamber, a radiant heater in said reaction chamber,and an outlet conduit for said reaction chamber.

3. An apparatus for generating combustible gas comprising a mixingdevice, meansfor malntaining the delivery of unlike gases to said mixingdevice constant at different pressures, a distributingat their oppositeends discharge orices communicatng with said gasifying chamber, and anoutlet conduit communicating with said gasifying chamber inheat-interchanging relation to said input conduit.

FREDERICK P. WILSON, JR.

